A book of condolence is to be opened today at Ravenhill rugby ground in Belfast for the young player killed alongside his father and brother in a farming tragedy.Ulster Rugby star Nevin Spence, 22, was killed along with his 30-year-old brother Graham, who is married with two children, and their 52-year-old father Noel.Floral tributes were yesterday left at Ravenhill by fans, and later heartbroken relatives of the three men said they had died trying to save each other